GB902564A - Improvements in or relating to apparatus for examining moving articles - Google Patents

Abstract

902,564. Television. ELECTRIC & MUSICAL INDUSTRIES Ltd. Oct. 1, 1958 [Oct. 5, 1957], No. 31230/57. Class 40 (3). [Also in Group XX] Apparatus for examining a moving article comprises a charge storage device including a charge storage electrode, means for directing invisible radiant energy on to an inspection field through which the article moves, image projecting means for causing the energy which passes through said field to form a focused image on and so charge said electrode, and means for scanning the charge image so formed to generate a signal representative of said image, the image projecting means including a movable image deflecting means arranged to move so that when the article is moved across the inspection field at a steady velocity the image formed on the electrode is stationary or relatively slowly moving during alternate intervals and relatively rapidly moving during the intervening intervals. As shown, the web 1, e.g. of metal from a rolling mill, is examined with a beam of X-rays from the tube 3 and a moving image is formed on a fluorescent screen 4, this image by means of lens 7 and rotating optical compensating reflecting polygon being presented as a succession of stationary frames on a television pick-up tube 8 of the Vidicon type having a photo-conductive storage electrode, the resulting image being scanned and displayed on a viewing tube 10 having a long decay screen. In another arrangement for examining photographic film, the radiation source employed is an infra-red lamp and the transmitted radiation is reflected directly by the rotating polygon. If the pick-up is a tube of insufficient resolution for the details to be observed, the field may be divided optically into two or more parts and a separate pick-up tube used for each, the signals derived from these tubes being used to operate a single viewing tube or separate viewing tubes. Instead of feeding the video signals to a viewing tube, they may be used to modulate the electron writing beam of a tube having a storage electrode and the charges subsequently reconverted into electrical signals for operating a viewing tube by scanning the electrode with a reading beam or by flooding the storage electrode with electrons, the resulting modulated flood being projected on to a fluorescent screen.